Tuning Impact 500mm with slug power kit?

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Deadlands

Deadlands

Member
Apr 17, 2020
43
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HI, United States
Anyone have good results with the slug power kit on an Impact MK2 with 500mm barrel in .22? Initially my Impact started out with a 700mm .25 on which I installed the slug power kit to shoot heavy slugs. It worked out but I wanted to make it a little more backyard friendly when I didn’t need 75 fpe, so I bought the 500mm barrel kit. I left on the slug power kit hammer weight and light valve spring, but with the 500mm barrel shooting 18.1 JSB pellets, it seemed like it’s wasting air with way too much hammer spring. Closing down the valve seems to be almost ineffective. I’m looking to be able to shoot pellets at a modest speed quietly, but also be able to change the barrel and pin probe to .25 700mm and shoot the heavy slugs without having to put the power kit in and take it out. 
 
The light valve spring is for high power the heavy valve spring is for low power. The light spring does little as you have said so use the heavy one and crank it down. If that does not get you to a low enough power level check out what I did below;

When I switched from high power .25 with a 700mm barrel 75-85fpe to a .22 500mm and 15 to 32+fpe I pulled my hammer spring shim and put the the heavy valve spring back in. Then I lowered my reg from 135 to 110bar and dialed my hammer spring down. Now the gun easily adjusts for my pellet weight choices in the 15-32+fpe range without a problem.
 
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This is pretty much what I wanted. Started off with a .22 700mm set up with the power kit for the JSB knockout shooting at 1024 fps but wanted to shot JSB 18's when I didn't need the fpe. I got a 500mm kit that has a dual transfer port from talontune. I'm still wasting air on the 500mm but having a DonnyFL emperor or Ronin with the Huggett Dedicated Shroud to quiet it down. The reason for the Huggett is that I'm not allowed to hunt with a moderator stated by the Department of Environmental Conservation. So I can take off DonnyFL on public land but still have a Shrouds Moderator



riron fx.1630028583.jpg

 
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Thanks for the replies! I pulled the power kit as I don’t think it’s really needed with my 500mm barrel for now. As more of a convenience I wanted to see if I could get away with leaving the hammer weights on with the short barrel and still get an efficient, quiet tune. I’ll have to try dropping reg pressure and putting in the stronger valve spring.
 
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The light valve spring is for high power the heavy valve spring is for low power. The light spring does little as you have said so use the heavy one and crank it down. If that does not get you to a low enough power level check out what I did below;

When I switched from high power .25 with a 700mm barrel 75-85fpe to a .22 500mm and 15 to 32+fpe I pulled my hammer spring shim and put the the heavy valve spring back in. Then I lowered my reg from 135 to 110bar and dialed my hammer spring down. Now the gun easily adjusts for my pellet weight choices in the 15-32+fpe range without a problem.
Click to expand...

Question.....

I have heard mixed things about the slug kit bc how the pin probe pushes in slugs inconsistently and can cause flyers. However, would you recommend JUST putting in the lighter hammer spring, opening up the pellet probe and installing either Huma Air or Ernest's transfer port? Basically what I'm asking is the main piece you REALLY want from the slug kit the lighter hammer spring?? 
 
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"Putting in the lighter hammer spring, opening up the pellet probe" is what I did on my .25 with the 700mm barrel and it werqed out very well. I also installed a 1.25mm brass hammer spring shim. Supreme accuracy at 100 yards at 74fpe and more power on tap if I wanted it. Yes, the only piece I kept from the kit, after installing the the pin probe and having it push a slug down my T-port and jamming up my gun big time, was the spring.

I did not install the Huma or Ernest transfer port as I had already done a good job on opening mine up. I was not aware of the fliers occurring because of the pin probe.

Pin probe adjustment and slug length would be critical for the most fpe output, constancy and best accuracy.

As for the 500mm .22 barre,l changed over to later, I found stock T-port to be fine, because of the short barrel, and changed back to the heavy valve spring to limit the power a bit.

The only thing I would actually recommend, after all of this, is that you don't use the pin-probe with an already ported T-port. Install the pin probe only with a stock or the Huma or Ernest T-ports.

https://www.airgunnation.com/topic/the-infamous-slug-power-kit-on-my-gen1-impact/?referrer=1
 
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"Putting in the lighter hammer spring, opening up the pellet probe" is what I did on my .25 with the 700mm barrel and it werqed out very well. I also installed a 1.25mm brass hammer spring shim. Supreme accuracy at 100 yards at 74fpe and more power on tap if I wanted it. Yes, the only piece I kept from the kit, after installing the the pin probe and having it push a slug down my T-port and jamming up my gun big time, was the spring.

I did not install the Huma or Ernest transfer port as I had already done a good job on opening mine up. I was not aware of the fliers occurring because of the pin probe.

Pin probe adjustment and slug length would be critical for the most fpe output, constancy and best accuracy.

As for the 500mm .22 barre,l changed over to later, I found stock T-port to be fine, because of the short barrel, and changed back to the heavy valve spring to limit the power a bit.

The only thing I would actually recommend, after all of this, is that you don't use the pin-probe with an already ported T-port. Install the pin probe only with a stock or the Huma or Ernest T-ports.

https://www.airgunnation.com/topic/the-infamous-slug-power-kit-on-my-gen1-impact/?referrer=1
Click to expand...

I have heard that the pin does not always push the pellet in straight or there are always issues with how far the slug gets pushed bc the small surface area on the pin?!....I dunno lol but I know a few people who took theirs out, bc it did nothing or had an adverse effect.

Can I buy JUST the lighter hammer spring and weights? Or do I need to get the entire slug kit if I want to the hammer spring? 
 
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